In general, in image forming devices such as laser printers and digital copiers, a laser beam is applied to a photoconductive member to correspond to data of an image to be printed, thereby forming an electrostatic latent image on the photoconductive member.
In order to facilitate maintenance of the devices and reduce the maintenance cost, both or one of a photoconductive drum and a developing roller can be embodied as a replaceable cartridge to the image forming device. For example, a developer cartridge having a developing roller is attached to the image forming device, or a developer cartridge is attached to a photoconductor cartridge having a photoconductive drum to form a process cartridge and then the process cartridge is attached to the image forming device.
At the time of forming an image by supplying a toner to an electrostatic latent image, it is necessary that the developing roller comes in uniform and precise contact with the photoconductive drum in the axis direction. However, in the structure that the photoconductor cartridge, the developer cartridge, or the process cartridge can be replaced, the distribution of the contact force in the axis direction may not be uniform. Therefore, there is provided that a developing-roller pressing mechanism for pressing the developing roller to the photoconductive member precisely and uniformly in the axis direction even after replacing the cartridges is disposed at one position or plural positions of the image forming device or the cartridges. Such a mechanism is disclosed, for example, JP-A-2000-250378.
The process cartridge or the developer cartridge thereof may include a memory unit that stores information such as an amount of toner and characteristics of members useful for easily and punctually performing the replacement or maintenance of the cartridges. Such a memory unit is disclosed, for example, JP-A-8-211818. In response to a request for performance or a decrease in cost, a contact IC chip may be employed as the memory unit. In this way, when the memory unit electrically connected to the main body is provided, it is necessary to make a stable contact between a terminal of the memory unit and a terminal of the image forming device to allow the memory unit to normally work.
However, when an electrical contact of the memory unit is disposed independent of the developing-roller pressing mechanism of JP-A-2000-250378, the pressing force of the developing roller may not be balanced and thus the developing roller may not be pressed to the photoconductive member uniformly in the axis direction.